Squeezing an exercise ball between your feet for this back-strengthening move will help to tone the legs even more.
- Lie on your belly, and hold an exercise ball between your feet. Engage your abs, and extend your arms straight out in front of you.
- As you inhale, squeeze the ball and lift your knees, arms, and chest off the floor. Hold for a count of 10, and then slowly release your body back to the floor.
- Repeat for three sets of 10 lifts.